Various types of intravenous (IV) therapy have been used to administer medical fluids and withdraw bodily fluids from patients. IV therapy has been used for purposes such as maintenance of fluid and electrolyte balance, transfusion of blood, administration of nutritional supplements, chemotherapy, and administration of drugs and medications. Specifically, fluids have been administered intravenously by injection through a hypodermic needle, or intermittently or continuously by infusion using a needle or catheter. The most common intravenous access method utilized by clinicians has been the peripheral IV catheter.
Peripheral IV catheters are made of soft, flexible plastic or silicone, generally between fourteen to twenty-four gauge in size. In conventional venipuncture procedures, a catheter is inserted into a vein in the patient's hand, foot, or the inner aspect of the arm or any vein in the body that will accept an IV catheter. In order to properly place the IV catheter into a patient's vein, a sharp introducer needle is used to puncture the skin, tissue, and vein wall to provide a path for placement of the catheter.
Referring to FIGS. 1 and 2, a prior art conventional IV safety needle assembly 20, configured for insertion of an “over-the needle” catheter 22, is depicted. The catheter 22 is operably coupleable to the safety needle assembly 20, in part by positioning the catheter 22 coaxially over the needle 24 of the safety needle assembly 20. The catheter 22 thus rides with the needle 24 through the skin, tissue, and vein wall and into the patient's vein. Often, the insertion end of the catheter 22 is tapered in an effort to minimize the amount of force required to insert the catheter 22 into the biological site.
The catheter 22 can include a catheter hub 30, which can be selectively coupled to a portion of the safety needle assembly 20. Catheter hub 30 is sometimes configured to control the flow of fluid through the catheter 22 via an internal fluid passageway that runs substantially parallel to the longitudinal axis of the catheter hub 30. In some embodiments, the fluid passageway includes a septum or valve to enable sealing of the fluid passageway to restrict or prevent bodily fluid from leaking out of the catheter hub 30 when the catheter 22 is inserted into a patient's vein and the needle 24 is removed.
When the needle 24 pierces the vein, blood will “flashback” through the needle 24 and into the flash chamber 26. Thus, once the clinician observes this flashback of blood, the clinician will know that the catheter 22 and needle 24 have been inserted in the vein. The catheter 22 can be advanced further into the vein as desired and the needle 24 can then be withdrawn from the catheter 22.
In addition to placement of an IV catheter, samples of the patient's blood are often obtained (e.g., for testing, blood typing or other analysis of a patient's condition). Such analysis frequently involves testing the blood for the presence of certain characteristics, such as the presence or amount of one or more constituents, or to determine the level of one or more parameters. For many of these blood tests, only a small sample of blood is required. After the IV catheter has been inserted, the clinician may obtain a blood sample through a variety of methods. One method is to have the patient endure another needle stick either by a needle and syringe to draw an aliquot of blood, or by pricking the patient's finger with a lancet for a few drops of blood.
Because some IV catheters of the prior art include an integrated flash chamber 26, another method is to enable access to the blood within the flash chamber 26 after the catheter 22 and needle 24 have been inserted into the patient's vein. Usually the proximal end of the flash chamber 26 is blocked by a flash plug 28. The flash plug 28 typically includes a filter material that enables air to vent from the flash chamber as the blood or fluid fills the chamber, but inhibits the blood or fluid from passing from the flash chamber 26.